Warnings aplenty in Joshimath before spiralling collapse

Days after the administration took note of cracks in buildings in Uttarakhand's 'sinking' town Joshimath, two precariously standing hotels in the subsidence-hit town were listed to be demolished on Tuesday after families were evacuated. However, the demolition could not go ahead amid protests from owners and locals on the issue of compensation, while more were rescued from the danger zone as the number of affected houses rose to over 700.

. Experts and residents have long warned that large-scale construction in and around the town, including work for power projects by companies such as state-run NTPC, could lead to land subsidence-- a phenomenon wherein the ground surface sinks or settles down.

. Nearly 700 houses in the town in the state of Uttarakhand have developed cracks and some 400 people have been moved to safer locations.

. Also Read: Joshimath a warning. Rethink development

. Despite environmental vulnerabilities, a number of hydro-power plants were sanctioned around Joshimath, the biggest of which is NTPC’s 520 MW Tapovan-Vishnugad project on Dhauliganga river that experienced the February 2021 flash flood killing more than 200 individuals.

. While the Tapovan Vishnugad hydel dam has been attributed as the major trigger for the subsidence, tunnelling work for the Char Dham project has also added to the town's woes.

. However, experts had warned about the dangers to the city long before :

. 1976: Mishra Committee Report

. The first report in 1976, titled 'Mishra Committee report' stated that Joshimath is situated on a deposit of sand and stones, all the while lying on an ancient landslide and is unsuitable for a township. The undercutting of Alaknanda and Dhauliganga rivers have also played a major part to bring landslides.

. “Joshimath is a deposit of sand and stone — it is not the main rock — hence it was not suitable for a township. Vibrations produced by blasting, heavy traffic, etc., will lead to a disequilibrium in natural factors…” the report said.

. 2001: NRSA's landslide hazard zonation mapping

. A detailed zone map of the area was submitted back in 2001, to warn the Centre on the underlying dangers of such areas. The study was done with remote sensing and Geographic Information System (GIS), with the help of 12 of the top scientific organisations, which includes the National Remote Sensing Agency (NRSA).

. 2006 - 'Joshimath localised subsidence and active erosion of the AT Nala'

. A scientific report from 2006 had warned that the town of Joshimath is sinking 1 cm every year.

. In the report, Joshimath's 124.54 sq km area was divided into six parts based on their vulnerability to landslides. Out of which, 99 per cent of the total mapped area was identified as landslide-prone in various degrees, while 39 per cent of the area was of high-risk, 28 per cent of moderate risk and 29 in low risk.

. Also Read: Joshimath hoteliers oppose 'abrupt' demolition move, demand one-time settlement plan

. "The underground seepages, erosion by the nalas and several types of anthropogenic activities have made the region weak to the extent that one block of this slope wherein Kamet, Sema villages and the town Joshimath are located, is sliding at a reported rate of more than 1 cm/year," stated the report. The report even suggested for the relocation of families from that region.

2022: Satellite images

. Over the last 18 months, the hill town of Joshimath has been sinking at a very high rate of 6-6.5 cm every year, a new study has shown.

. Indian space scientists on Tuesday presented satellite images showing what they described as a “significant” subsidence rate in Joshimath for over 18 months – between July 2020 and March 2022.

. "Joshimath is sinking at a rate of 6-6.5 cm per year as per the satellite images. The reason could be manifold. We have been looking at the satellite data since 2015, but the analysis would take some time,” a scientist at Indian Institute of Remote Sensing, Dehradun told DH.

. What next?

. The Centre on Tuesday announced that it will install micro seismic observation systems at the landslide-prone town.

. Earth Sciences Minister Jitendra Singh made the announcement at the India-UK Workshop of Geosciences and said the observation systems will be in place by Wednesday. He said in the next five years, 100 more such seismological centres will be opened across the country for improving real time data monitoring and data collection.

. Officials said seismic microzonation study for the area would generate risk resilient parameters for safer dwellings and infrastructure.

. They said Joshimath falls under the highest seismic hazard Zone V as it experiences continuous seismogenic stresses.

. Joshimath already seismologically sensitive

. Seismic energy generation due to micro-earthquakes may have weakened the strength of the rocks as Joshimath is located in the earthquake rupture zone of the 1999 Chamoli earthquake, they said.

. Climatic factors such as excessive precipitation and flow of water from mountains into massive cracks and fractures in the sub-surface rocks lead to widening of cracks and hastening the slip in rock material, the officials said.

. (With agency, DHNS inputs)

Warnings aplenty in Joshimath before spiralling collapse

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